On the relation between orbital structure and observed bar morphology     

P. A. Patsis 《Monthly notices of the Royal Astronomical Society》2005,358(2):305-315

We investigate the morphological relation between the orbits of the central family of periodic orbits ( x ₁ family) and the bar itself using models of test particles moving in a barred potential. We show that different bar morphologies may have as a backbone the same set of x ₁ periodic orbits. We point out that by populating initially axisymmetric stellar discs exponentially with test particles in circular, or almost circular motion, we may end up with a response bar which reveals a shape different in crucial details from that of the individual stable x ₁ orbits. For example, a bar model in which the x ₁ orbits are pure ellipses may have a much more complicated response morphology. This depends on the particular invariant curves around x ₁, which are populated in each model.  相似文献   

青藏块体东北缘地壳水平运动状态   总被引：10，自引：6，他引：4  

崔笃信  王庆良  王文萍 《大地测量与地球动力学》2004,24(3):29-34

应用青藏块体东北缘1999～2003年多期GPS观测资料，计算了不同时段GPS点水平运动速率。通过分析发现：甘青块体可分为东部块体和西部块体，东、西部块体的运动状态存在明显的差异；受2001年11月14日昆仑Ms8．1地震的影响，震后地壳运动状态发生了明显的改变。  相似文献   

秦岭及黄土区的栎林与发育气候     

《地球科学与环境学报》1996,(1)

  相似文献   

桐柏县固庙—新集1：20万金银异常评价方法及效果     

韩存强  年平国 《河南国土资源》1996,(1)

随着河南区域化探扫面工作的结束，异常评价是摆在我们面前的当务之急。近年来，随着地质工作的不断深入，我们在异常评价程序及方法上作了一些探索，下面以桐柏县固庙—新集１：２０万金银异常评价方法及效果为例，重点加以讨论。  相似文献   

Current plate motions   总被引：57，自引：0，他引：57  

C. DeMets  R. G. Gordon  D. F. Argus  S. Stein 《Geophysical Journal International》1990,101(2):425-478

  相似文献   

元岭金矿蚀变破碎带特征及其找矿意义     

刘红樱  周顺之  胡受奚  王群昌 《河南国土资源》1996,(2)

根据对元岭金矿三条蚀变破碎带一般地质特征、微量元素特征的对比研究，并借鉴邻近矿区蚀变破碎带的矿化特征，本文阐明了元岭蚀变破碎带矿化的有利构造部位，总结了蚀变破碎带特征与矿化强度之间的关系，指出蚀变破碎带的矿化蚀变元素为中低温组合，矿化蚀变愈强则参与元素的种类愈多、数量愈大。围岩性质对矿化蚀变有一定影响，围岩中的易迁移亲铜元素和亲硫铁族无素对矿化有利。据此，为进一步成矿预测、评价蚀变破碎带的含矿性提供依据。  相似文献   

企鹅珍珠贝人工苗生长的初步观察   总被引：3，自引：0，他引：3  

梁飞龙  毛勇  余祥勇 《广东海洋大学学报》2001,21(1):6-9

为了解企鹅珍珠贝生长规律，观察了壳高2.5～5.0mm的出池幼苗，按月测量其生长参数和成活率，以及环境因子。结果表明，企鹅珍珠贝生长最快的月份为7～11月和次年4～6月，壳长，壳高和壳宽月均增加量分别为3.8～13.0mm、4.7～11.2mm、2.3～3.8mm，月成活率97.8%～98.6%。企鹅珍珠贝生长最慢月份是11月至次年3月。  相似文献   

Simulations of deep pencil-beam redshift surveys     

N. Yoshida  J. Colberg  S.D.M. White  A.E. Evrard  T.J. MacFarland †  H.M.P. Couchman  A. Jenkins  C.S. Frenk  F.R. Pearce  G. Efstathiou  J.A. Peacock  P.A. Thomas 《Monthly notices of the Royal Astronomical Society》2001,325(2):803-816

We create mock pencil-beam redshift surveys from very large cosmological N -body simulations of two cold dark matter (CDM) cosmogonies, an Einstein–de Sitter model ( τ CDM) and a flat model with Ω₀=0.3 and a cosmological constant (ΛCDM). We use these to assess the significance of the apparent periodicity discovered by Broadhurst et al. Simulation particles are tagged as 'galaxies' so as to reproduce observed present-day correlations. They are then identified along the past light-cones of hypothetical observers to create mock catalogues with the geometry and the distance distribution of the Broadhurst et al. data. We produce 1936 (2625) quasi-independent catalogues from our τ CDM (ΛCDM) simulation. A couple of large clumps in a catalogue can produce a high peak at low wavenumbers in the corresponding one-dimensional power spectrum, without any apparent large-scale periodicity in the original redshift histogram. Although the simulated redshift histograms frequently display regularly spaced clumps, the spacing of these clumps varies between catalogues and there is no 'preferred' period over our many realizations. We find only a 0.72 (0.49) per cent chance that the highest peak in the power spectrum of a τ CDM (ΛCDM) catalogue has a peak-to-noise ratio higher than that in the Broadhurst et al. data. None of the simulated catalogues with such high peaks shows coherently spaced clumps with a significance as high as that of the real data. We conclude that in CDM universes, the regularity on a scale of ∼130  h ⁻¹ Mpc observed by Broadhurst et al. has a priori probability well below 10⁻³.  相似文献   

Large-scale structure in the ELAIS S1 Survey     

E. A. Gonzalez-Solares  S. Oliver  C. Gruppioni  F. Pozzi  C. Lari  M. Rowan-Robinson  S. Serjeant  F. La Franca  M. Vaccari 《Monthly notices of the Royal Astronomical Society》2004,352(1):44-48

  相似文献   

The spectral variability of Triton from 1997-2000     

Michael D Hicks  Bonnie J Buratti 《Icarus》2004,171(1):210-218

We present the results of a three-year observational program of long-slit spectroscopy and UBVRI photometry of Triton. We find evidence for short-lived albedo variations at wavelengths less than 0.5 μm with the most notable reddening event measured in October 1997 and “normal” colors returning by May 1998. We report a possible variation in the relative 0.73/0.89 μm methane absorption band strengths, suggesting that the transport or denudation of this species may play a major role in the reddening events.  相似文献